1. Field of the Invention
The present invention relates to a method of punching a damper to be attached to an objective portion of, for example, a head suspension of a hard disk, to a punching apparatus used for the method and to an attaching apparatus with the punching apparatus.
2. Description of the Related Art
A hard disk drive has a disk and a head suspension for supporting a head. The head suspension allows the head to slightly float from the disk to read/write signals when the disk rotates at high speed. In such head suspension, data errors are likely to occur due to off tracks that are generated by turbulence (wind excitation), a natural vibration or the like at the time of the rotation of the disk.
To solve this problem, JP2001-067635A discloses a vibration damping technique that attaches a damper to a head suspension, the damper including a viscoelastic body layer and a constraint layer laminated on the viscoelastic body layer.
When the damper is attached to the head suspension, a damper material is prepared on an exfoliative member that is attached on the viscoelastic body layer side of the damper material in advance. Then, dampers are punched out from the damper material having a required shape one after another. The punched dampers are once aligned on a liner, and an attaching apparatus automatically or a worker with a pair of tweezers etc. manually picks them up to attach or stick on objective portions on the head suspensions, respectively.
In this regard, the applicant has proposed an automatically-attaching apparatus that automatically punches out and attaches a damper as JP2009-176347A.
The automatically-attaching apparatus is used for a damper material with a conventional constraint layer that is relatively thin and allows the damper to be punched out without cracks on the constraint layer.
Dampers, however, may have a thicker constraint layer to be applied to head suspensions as products in order to meet various requirements for head suspensions. In this case, the damper material also has a thicker constraint layer and involves a problem that the constraint layer of the punched damper cracks when punching out the damper from the damper material.
FIG. 12 is a magnified photograph showing a part of a cutting surface of a punched damper that is magnified 300 times, and FIG. 13 is a magnified photograph showing the same part that is magnified 500 times. As is apparent from FIGS. 12 and 13, there is a crack C in a thicker constraint layer.
FIGS. 14 and 15 are partial planar photographs showing a damper D with cracks that is stuck to an objective portion of a head suspension HS. In the photographs, whitened portions are the cracks C.
The cracks C occurred in this way affect the damping property of the damper to cause the deviation or bias in the damping characteristics of the head suspension. A solution is demanded for such cracks.